1. Field of the Invention
This invention generally relates to waveguides. More particularly, this invention relates to transitions between microstructure-doped waveguides and other types of waveguides.
2. Description of the Related Art
Light offers many advantages when used as a medium for propagating information, the foremost of which are increased speed and bandwidth. In comparison with electrical signals, signals transmitted optically can be switched and modulated faster and can include an even greater number of separate channels multiplexed together. Accordingly, lightwave transmission along optical fibers is widespread in the telecommunications industry. In an exemplary fiber optic communication system, a continuous wave (CW) beam of light may be emitted from a laser diode and modulated using an electro-optical modulator that is driven by an electrical signal. This electrical signal may correspond to voice or data which is to be transmitted over a distance between, e.g., two components in a computer, two computers in a network, or two phones across the country or the world. The light travels in an optical fiber to a location where it is detected by an optical sensor, which outputs voltage that varies in accordance with the modulation of the optical beam. In this manner, information can be rapidly transported from one location to another. To increase data throughput, numerous optical signals at different wavelengths can be multiplexed and transmitted together along a single optical path. This optical path can be switched selectively and varied to direct the optical signals to the appropriate destination.
Accordingly, various components have been developed to process and manipulate optical signals. Examples of such components include modulators, switches, filters, multiplexers, demultiplexers to name a few. Many of these components can be formed on a substrate. Accordingly, it is highly desirable to combine a variety of such components into a system that is integrated onto a single substrate. In such a system, optical waveguides theoretically could be used to propagate optical signals between components on the substrate. Waveguides can be fabricated in a wide variety of geometries, shapes, and configurations. What is needed are structures for efficiently optically connecting waveguides having different geometries.